Thermal processing is commonly practiced in the semiconductor industry. Semiconductor substrates are subjected to thermal processing in the context of many transformations, including deposition, doping, activation, and annealing of gate source, drain, and channel structures, siliciding, crystallization, oxidation, and the like. Over the years, techniques of thermal processing have progressed from simple furnace baking, to various forms of increasingly rapid thermal processing (RTP), spike annealing, as well as other thermal processes.
As the critical dimensions of semiconductor device features continue to shrink, more stringent constraints on thermal budgets are required during thermal processes. Many of the aforementioned thermal processes utilize lamp heating in the form of a lamphead consisting of a plurality of light sources positioned to direct radiant energy toward a substrate. However, the irradiance pattern of the light sources is sometimes irregular in conventional lampheads, which creates irregular heating of the substrate.
What is needed is a method and apparatus that enables improved radiance control of the lamphead within a thermal process chamber.